I'd say you did pretty good. I wish I had friends like that! Value to serious collectors is crucially dependent on grade. You can get some idea from the website link below but, as in most catalogues, valuations for coins from this era usually start at "Fine" (F), except for rare dates/varieties. Mostly your coins are in the next category down as "Very Good" (VG), with some approaching "Fine", apart from the 1890 halfcrown which is sufficiently worn/damaged that it has no collector interest.
Coins in the lesser grades don't usually command big premiums over their silver content but, to put that in context: all of these coins are .900 fine silver and at current prices the bullion value for the crowns would be about £15 each and the halfcrowns... guess what?... half that. So, you have well over £65 of silver there, even without any numismatic premium.
for coins I will often just go to EBAY and do a search for the "sold" listings (advanced button). It will give you a good idea of current value and market.
here is a similar George III half crown that sold in May.
